What this RC unit does in the panel
The Siemens SENTRON 5SM9325-6KK is a 2-pole residual current unit (RC unit) with an electronic, instantaneous trip design, rated 63 A at 400 V AC and 30 mA sensitivity, type A for AC and pulsating DC fault currents. It sits upstream of a downstream MCB or as a stand-alone residual current protection block in a 50 Hz distribution board — the 30 mA threshold covers personnel protection (indirect contact) per IEC 60364, while the 63 A continuous rating matches the feeder or submain it protects.
Thermal derating — what the temperature row tells you
This unit holds 58.59 A at both 40 °C and 45 °C, then begins a gradual derating curve: 56.7 A at 50 °C, 54.81 A at 55 °C, 53.55 A at 60 °C, 52.29 A at 65 °C, and 50.4 A at 70 °C.
No phase-out or last-time-buy notice is on record.
What type A means for the installation
That covers most modern loads with rectifiers — VFDs, switched-mode power supplies, LED drivers, washing machine electronics — where a simple AC-type RCD would be blind to the pulsating DC component. If your sub-distribution feeds any single-phase electronics, type A is the minimum requirement under IEC 60364-5-53.
Panel integration — 2-pole, DIN-rail footprint
Two-pole design (line and neutral switched) in the standard SENTRON 5SM9 modular housing. The electronic trip needs no external auxiliary supply — it self-powers from the line voltage. Verify the downstream MCB's breaking capacity coordinates with the RC unit's short-circuit withstand; Siemens recommends a 63 A or smaller MCB with at least 6 kA breaking capacity per the 5SM9 coordination tables.